Part 6 Section 2 LAYOUT OF SIGNALS Issued May 1995

2 Layout and Use of Signals

2.1 General frame is shown between the signalman and the . Locating the frame in this position has an Signals are provided to control the movement of effect on the numbering of the equipment con- and to inform the driver whether it is safe trolled by the box. to proceed. Their location is dictated largely by the track layout, the relevant Government Department’s minimum requirements and, to 2.1.2 Lever numbering some extent, by the frequency of movements. Coupled with this are the variations in practice The levers in a frame are arranged in a straight that occurred from company to company. At one line and numbered consecutively with number 1 end of the scale there were companies that provid- always on the signalman’s left as he faces the ed signals for every conceivable movement while frame. The normal position of the levers is back in others only used the bare minimum required by the frame and when a lever is pulled it is said to routine work. When a special movement was be reversed. As far as possible the layout number- required, companies supplemented the fixed sig- ing is arranged so that, for the commonest train nals with oral or written instructions and hand movements, the levers are pulled in numerical signals. order. Modellers basing their layouts on prototype The normal practice is to number the levers in locations can, with a little research, find out the the same order that the equipment controlled ‘lies positions and types of signal used including on the ground’. In Figure 2-1, down line trains changes that may have occurred over the years. approach from the left, hence the down line signals Where the layout is a ‘might have been’ the follow- occupy the low numbers. Similarly the up line sig- ing notes can give initial guidance to correct signal nals occupy the high numbers. The crossovers and location. However, for the layout to be fully their associated ground signals are located in the authentic it is necessary to study the practices of middle of the frame and provide a physical separa- the company being portrayed. Luckily, there is a tion between the two sets of running signal levers. considerable amount of information available in In addition to their numbers, levers are also railway literature and from specialist societies, identified by their colours which indicate the par- particularly the Signalling Record Society. ticular function that they perform. The standard colours are:- Distant signals Yellow 2.1.1 Signal box interior layout Stop signals Red When a lever frame is fixed in a box there are two Points Black positions that it can occupy: Point locks Blue • With the signalman facing the running lines so Detonator Placers Black with White chevrons that he can see the points and signals while Spares White operating the levers. This has a disadvantage in that the signal levers, track diagram, block instruments, etc. tend to obstruct his view. In 2.1.3 Facing point locks and fouling bars addition, he only has access to the windows at either end of the frame for giving instructions Facing points on running lines carrying passenger to drivers or shunters. traffic are required to be fitted with facing point locks. The lock mechanism consists of a bar fitted • With the signalman having his back to the run- between the point blades that has either one or ning lines so that by turning round he has an two holes in it. Where passenger traffic used only uninterrupted view and access to all windows one of the facing roads and only non-passenger overlooking the line. traffic used the other road, it was the practice to There are no hard and fast rules but the latter provide a one-hole lock bar. However, it has now method was more often adopted when planning become general practice to provide a two-hole lock new frames in early BR days. Where signal boxes bar locking facing points both normal and reverse, are shown on track diagrams their orientation is regardless of traffic considerations. A sliding bolt, indicated by representing the frame by a thick line connected to a locking lever in the signal box, fits and the signalman by a dot. In Figure 2-1 the into the holes locking the points. In modern prac-

Compiled by A. Garraway, J. R. Hadwin, D. Strivens, M. H. Walshaw. 6 - 2 - 1 Drawings devised by K. Sheale Artwork by Kensington Graphics tice when a facing point lock lever is normal in the provides an indication in addition to, or in place of, frame, the points are unbolted and free to be track circuiting. moved. When the lever is reversed the bolt is inserted and the points are locked. To reverse a set of facing points, the signalman 2.2 Typical Through Station first restores the locking lever to normal to unbolt Layouts the points. He then reverses the points and revers- es the locking lever. This inserts the bolt into the 2.2.1 Semaphore signalling at a through second hole in the stretcher bar locking the point station in the reversed position. To prevent points being moved under a train, Figure 2-1 shows the mechanical signalling that mechanically worked points are fitted with a foul- might be planned for a through station with two ing bar. This consists of a bar longer than the main crossovers and a connection. The sig- longest wheelbase (usually some 16m, or nals have been numbered and their functions 50ft, in length) which lies alongside the inside could be described as follows: edge of one of the running rails and is connected to 1. Down distant the facing point lock mechanism. Unbolting a fac- 2. Down home ing point lock causes the fouling bar to rise into 3. Down starting the flangeway. Should a train be passing, the foul- 4. Down advanced starting ing bar would be prevented from rising and, in 5. Call on to down platform turn, prevent the bolt from being withdrawn and 6. Shunt ahead down line the points moved. In modern practice, particularly 7. Shunt, up line to down platform with the advent of long modern coaching stock, the 8. Crossover, up line to down platform fouling bar has been replaced by electrical locking 9. Shunt, down platform to up line using the track circuits. 10. Shunt, up platform to down line 11. Crossover, up platform to down line 12. Shunt, down line to up platform 2.1.4 Electric depression bar 13. Shunt, down sidings to down line 14. Crossover, down sidings exit This device consists of a bar which lies in the 15. Shunt, down line to down sidings flangeway level with the running rails. It is fitted 16. Call on to up platform with electrical contacts which are activated when 17. Up advanced starting the bar is depressed by the weight of a 18. Up starting or other vehicle. It is found at the end of bay plat- 19. Up home forms and is used to remind the signalman of the 20. Up distant presence of a locomotive or vehicle standing there. It is often provided where, due to deposits on the Note 1: The shunt ahead signal (6) only needs to rails, the track circuiting is erratic in operation. It be provided if the distance between the siding points and the advanced starter (4)

13 Yellow 14 1 5 2 3 6 4 Platform 14

Down 8 11 7 10 9 12 15 Up 8 11 Platform 17 18 19 16 20 Signal Box FIGURE 2-1 Typical Through Station with Semaphore Signalling.

6 - 2 - 2 Part 6 Section 2 LAYOUT OF SIGNALS Issued May 1995

is less than the normal length of train tant signal as a separate entity has virtually dis- that uses the siding. appeared. (Section 1.7 covers these changes). Note 2: If a train standing on the down line in the The introduction of three and four aspect sig- rear of advanced starter (4) was regularly nalling using automatic block working would often required to back into the down platform require the new signals to be located in different as far as ground signal (9), a third ground positions to the semaphores that they replaced. signal, in addition to (12) and (15), would These changes occurred where the new block sec- be needed to cover this movement. tions differed in length and/or to improve signal However, some railways, notably the SR sighting for the drivers benefit. In addition, many and the MR (prior to 1906), used a single of the subsidiary signals have been eliminated, for ground signal to cover all three routes on example in some areas the main signal is used to the principle that the driver knew where control Shunt Ahead movements. he wished to go and could see the lie of A variation that has been used for the Shunt the points. Again, company practice needs Ahead and Calling On signals is shown in the to be checked. drawing. In place of the single yellow or the two diagonal white lights described in Section 1.9, Note 3: Although not shown in the figure, a two some areas make use of a modified standard colour aspect green /yellow colour light distant light ground signal bracketed out from the post was sometimes used (from the 30’s to below the main signal. The normal aspect is with date) to replace a semaphore distant all lamps out. When the signal is pulled ‘off’ all when renewals were required, particular- three lamps are illuminated. The bottom right and ly where the signal was some distance top left show a white light, replicating the two from the box. diagonal lamps, while the bottom left shows the letter S or C depending on the signal’s function. 2.2.2 Colour light signalling at a through The signals in Figure 2-2 have been numbered station and their functions could be described as follows:

Figure 2-2 shows a form of three aspect colour 1. Down distant light signalling that might be found at a through 2. Down first home station similar to Figure 2-1 above. Some early two 3. Down second home aspect colour light installations tended to be copies 4. Down starting of their semaphore predecessors and include 5. Call on to down platform green/yellow distants. However, these were gener- 6. Shunt ahead down line ally transitory arrangements and, where the vol- 7. Shunt, up line to down platform ume of traffic demanded it, the introduction of 8. Crossover, up line to down platform three and four-aspect track circuited block instal- 9. Shunt, down platform to up line lations, often controlled from a central power box, 10. Shunt, up platform to down line became the norm. As a result, the colour light dis- 11. Crossover, up platform to down line

15 Yellow Headshunt c 14 s 1 5 2 3 6 4 Platform 14

Down 8 11 13 12 7 9 10 Up 8 11 Platform 17 18 19 c 16 20

FIGURE 2-2 Typical Through Station with Colour Light Signalling.

6 - 2 - 3 12. Shunt, down line to up platform or down 2.3 A Typical Branch Line Terminus sidings 13. Route indicator (see note) Few modellers have the space to portray a busy 14. Crossover, down sidings exit main line, the majority have to make do and select 15. Shunt, down sidings to down line a prototype that they can house and which in 16. Call on to up platform many cases is some form of single track branch 17. Up starting line terminus. Even here the traffic volume can 18. Up second home vary considerably: from the outer suburban branch 19. Up first home with a relatively frequent passenger and regular 20. Up distant freight service to the almost moribund rural line with, at most, three or four passenger trains each Note: Modern practice is to use a single ground day and a twice weekly freight service. The former signal (12 in the above diagram) with a would need to be fully signalled whereas in the lat- route indicator (13) to indicate movements ter case the signalling could be minimal or non- from the down line to the up platform or the existent. down sidings. The route indication is auto- Because of this wide variation it is only possi- matically selected in accordance with the lie ble to suggest some basic rules for signal location. of the points. These include:- • Where passenger trains have a choice of route With the growth in the use of multiple unit the splitting signals must have full sized arms. passenger stock, the use of push-pull working for (See Section 1.2.6). They need to be positioned main line trains and the virtual elimination of in the rear of the facing points, which would be local freight working, the need for the second fitted with facing point locks. As the fouling bar crossover to allow running round is lessened. is typically 16m (50ft) long, the splitting signal Rationalisation of the layout in Figure 2-2 could would need to be installed at least 16m (14ins see the right hand crossover eliminated together in model terms) in the rear of the point blades with ground signal 10 and route indicator 13. to allow sufficient clearance for the fouling bar. Unless passenger trains terminated and lay-over, the sidings could go as well. If needed for passen- • Converging junctions and turnouts must be pro- ger stock lay-over they would most likely be served tected by stop signals, either situated 400m by a facing cross-over which would be protected by (440yds) in the rear of the fouling point (as per facing point locks. Section 1.2.7) or just clear of the fouling point.

Back Road Reverse Points Worked Normal from Signal Box

Middle Road Hand Points Worked Locally Front Road

Goods Shed Road Parcels Bay Station Buildings Headshunt

Engine Spur Platform Road Main Line

Water Coal Rel. Road Spur Engine Release Road Crane Stage Engine Service Carriage Siding Road Turntable (if required) FIGURE 2-3 Typical Single Track Branch Terminus.

6 - 2 - 4 Part 6 Section 2 LAYOUT OF SIGNALS Issued May 1995

An example of the latter case would occur locomotive to run round the train this would take where adjacent platform roads with their atten- place using the platform road and the engine dant starters converge onto a single main line release road. This also means that the goods train • Generally there is a starting signal at the end of timing needs to be integrated with a slack period a platform, but it must be clear of the fouling in the passenger timetable to avoid blocking the point of any turnouts in advance of it. passenger train’s . • Other signals are installed, as necessary, as Note: With rationalisation of the services in later described in Section 1. years, assuming that the line had not been Assuming the maximum traffic requirements, axed, the passenger service would probably Figure 2-3 is a typical branch line terminus which be some form of DMU service requiring only might have been found up to the mid-late 60s. the platform road to be retained. If the The first step is to determine the types of train goods yard were also retained it would prob- that would use a terminus of this size. On the pas- ably be used for a specialist product and be senger side the regular service would be between reduced to two or three sidings only but pro- the terminus and the with the main line vision for running round would still need to or the nearest large town. The equipment used be available. could be as simple as a push-pull set which just Figure 2-4 is a repeat of the previous figure with shuttles back and forth or it could be a local car- the minimum number of signals needed to control riage set hauled by a separate locomotive. In the train movements within the station area. latter case there would need to be provision to run round the train. In addition, depending on the size and importance of the locality, there could be a 2.3.1 Arrival movements daily working to and from a major city using corri- dor stock and a main line engine. This latter could A down train arriving would first pass a fixed dis- require the engine service road to be supplied with tant signal requiring it to reduce speed as it a turntable. approached the terminus. The next signal sighted A goods yard as shown would probably only would be the home signal (1). In the case of a pas- require a daily trip working from the junction. senger train, the platform road should be clear and Because the goods yard has no provision for the the home signal would be pulled off in readiness to

4(a) 3 5 4(b)

7 6

FIGURE 2-5 Double Slip Variation.

10 Yellow Station Buildings Headshunt

9 15 (a) 7 14 12 8 Up

(a) 3 Down 11 5 (b) Yellow 12 13 (b) 4 Fixed Distant

1 2

FIGURE 2-4 Basic Signal Layout for Small Terminus.

6 - 2 - 5 allow the train to continue at reduced speed into ation, it could be manually operated by a local the platform. On arrival in the platform road, with lever and unsignalled. the train held clear of the engine release crossover A further variation that can occur concerns the fouling point, the engine would be detached and release road spur. Unless the spur is required to run forward to the engine spur ready to run round serve another facility like a loading bank then, in the train. order to save on material and maintenance, a In the case of a goods train approaching the number of companies, notably the GWR, would not terminus, particularly in the days of loose cou- install it and point (11b) of the crossover would plings and unbraked stock, it would commence either be a simple trap point working in conjunc- slowing once the fixed distant was sighted. The tion with point (11a) or eliminated completely. home signal (1) would remain on until the train Once on the release road the engine could had almost come to a stand to ensure that it was either go direct to the service road to pick up fuel under control before the signal was pulled off and water, passing the yellow permissive ground admitting it to the platform road. signal (5) set at on, or wait to move onto the main If arriving goods trains were required to enter line. the engine release road on a regular basis, a To complete the run round movement, miniature arm (2) could be set below the home sig- crossover (4) must be reversed and ground signal nal. Alternatively, if this movement only occurred (5) pulled off allowing the engine to return to the infrequently, a ground signal (2) would normally main line. Because crossovers (4) and (9) are fac- control the movement. (See inset). ing points on the running lines they would have facing point locks (3) and (8) with fouling bars fit- ted. These would require the engine (or train) to be 2.3.2 Movements within station limits clear of fouling bar (8) before crossover (4) and ground signal (5) are returned to normal. The Running round home signal (1) is then pulled off, allowing the The first movement after arrival is to release the engine to back on to its train. locomotive to allow it to either run round its train Ground signal (7) is shown as a separate or go to the engine service road. Having been ground signal in Figure 2-4, however, in practice it uncoupled it would draw forward to the engine could be located on a short bracket, adjacent to sig- spur clear of the release crossover (11). The control nal (2), just below the home signal (1). It would of this crossover can vary depending on local cir- normally be used to control backing movements cumstances. into the goods yard. (It was not unknown for some As shown the points and ground signal are companies to provide a disc or ground shunt signal numbered as though operated from the signal box. for each possible route and, depending on the However, because of the cost of rodding from the space available, they could be mounted side by signal box, it is possible that the engine release side or stacked vertically. Normally this type of crossover (11) and its associated facing point lock configuration would only occur in busy areas (12) would be controlled by a local ground frame. where shunting was carried out almost continu- This could also be due to the distance involved as ously rather than at the end of a single line points are not allowed to be mechanically worked branch). by rodding over a distance greater than 325m (350yds). Disposal of carriage stock. The frame would be unlocked from the signal If the train is a passenger train and is the last box by the signalman and the local levers would arrival of the evening it may need to be stabled then be operated by a member of the train crew. overnight. For this movement, when the engine The frame would normally have two levers, one had run round its train the starting signal (15) controlling the crossover and one the facing point would be pulled off to allow the train to draw for- lock. Where the movement is under the direct con- ward clear of fouling bar (3). Once clear, crossover troll of the train crew, the ground signal (13) would (4) would be reversed and the ground signal (2) not normally be installed. A modern variation is to would be pulled off to allow reversal into the car- have a further lever on the local frame which when riage siding. The un-numbered carriage siding released electrically from the signal box, unlocks point would probably be manually operated by a the frame mechanically when pulled. This is shunter. required to prevent the signalman ‘taking back’ his release until the use of the ground frame is Disposal of freight stock completed. In the case of a freight train, the process of run- On a quiet rural line, if the crossover were ning round and drawing forward along the main located beyond the end of the platform where it line clear of fouling bar (8) follows the same pat- normally would be clear of passenger vehicle oper- tern as described above. Reversing crossover (9)

6 - 2 - 6 Part 6 Section 2 LAYOUT OF SIGNALS Issued May 1995

and pulling ground signal (7) off allows the train to end would allow outgoing passenger trains to be be reversed into the freight yard. Once clear of the observed to ensure that all doors were closed cor- main line with crossover (9) restored to normal, rectly. However, as the line is a single track the the process of delivering the arrivals and collecting signalman needs easy access to a token exchange the departures can be carried out. The initial move platform to deliver and collect tokens controlling would be to dispose of the brake van which could movements along the branch. Position (a) provides be parked in the end of the parcels bay road. access for arriving but could require a Shunting moves into and out of the various sidings walk to reach locomotives standing in the sidings would be under the control of a shunter. To allow awaiting departure. If the box were located close to the engine and wagons to draw clear as required the down bracket signal in position (b) it would they can move into the headshunt past the permis- provide an easier approach to both arriving and sive ground signal (10) showing on. On completion departing locomotives. of the delivery and collection, the outgoing train Assuming that the box was located in position would be held clear of crossover (9) until departure (a) and contained a standard 15 lever frame, the time. levers would be numbered:-

Double slip variation 1. Home signal Stop arm The engine release road and carriage siding con- 2. Release road entry Miniature arm or red verge at a single point and are followed by a ground signal crossover with movements on to the main line con- 3. Facing point lock Plus fouling bar trolled by a ground signal (5). However, if due to space constraints the two points are combined to 4. Release road crossover form a double slip, then an additional ground sig- 5. Release road exit to nal would be required for the carriage road but, main line Yellow ground signal because the two routes converge, both signals 6. Spare would be red, non-permissive versions. The slip 7. Down main to goods yard Red ground signal would be operated from the signal box and require an additional lever. This variation is shown in 8. Facing point lock Plus fouling bar Figure 2-5. The additional ground signal would 9. Goods yard crossover also require an additional lever and these two, (6) 10. Goods yard exit Yellow ground signal and (7), would need to be located close to the exist- ing point levers associated with the crossover. This 11. Engine spur crossover would require the other lever numbers to be 12. Facing point lock changed unless there were sufficient spare levers 13. Engine spur to in the frame. (see 2.1.2 Lever Numbering). release road Red ground signal 14. Advanced starter Stop arm 2.3.3 Departure movements 15. Platform starter Stop arm If the box were located in position (b) the lever When departure time for the passenger train is numbering would be the reverse of that shown reached, on receiving permission from the box in above. advance, the advanced starter/section signal (14) and starter (15) would be pulled off allowing the train to enter the next section on its way to the junction. 2.4 Other Typical Layouts When the freight train is ready to leave, crossover (9) is reversed, the advanced starter/sec- The more complex track formations that occur in tion signal (14) would be pulled off allowing entry prototype practice are beyond the scope of these into the next section, followed by the ground signal notes but the following two examples cover track (10) being pulled off allowing exit to the main line. layouts that could occur in larger model railways.

2.3.4 Signal box location 2.4.1 to single track branch The actual position of the signal box will depend on the topography of the site but it would need to The points to note about this track layout, shown be located as close to the operations as possible, in Figure 2-6, are that the Up Distant (1) would particularly if the signalman has to flag certain only be pulled off for travel along the main line, movements. The position (a) close to the platform branch trains would reduce speed to pass it at cau-

6 - 2 - 7 8 Fixed 6 9

3 1 2 Up 4 5 Main

Down 7 11 12

FIGURE 2-6 Double Track with Single Track Branch leading off.

tion, and points (7) can only be reversed if points to a stand at their respective home signals (2 and (5) are also reversed. (In the event of a train over- 14) to ensure that they were under control and running, the collision point is moved away from then brought into the platform independently. If the main line, but there may be cases where this is trap points were provided they would work as a undesirable and the two points are not inter- pair with their respective loop points (8) and (9) locked). Where the diverging route does not have a and, as they are on running lines, they would be severe speed restriction, a separate branch distant protected by facing point locks and fouling bars. may be provided. This would entail additional levers in the signal Down line signals would normally be posi- box. tioned 400m (440yds) from the fouling point but The points at either end of the loop are set nor- may be brought nearer if traffic density warranted mally in the position shown on the diagram so it, e.g. SR suburban electric services. that, in the event of a train running past signals A box having a standard 12 lever frame would (2) or (14) at danger, it would continue on the cor- have the levers numbered as shown on the dia- rect line. Point (8) is shown as having an addition- gram with lever 10 being a spare. al fouling bar known as a clearance bar operated by the same lever. This is used to prove that a train on the up line is not foul of a train running 2.4.2 Single track on the down line. A train standing on the clear- ance bar would prevent lever 8 from being moved Figure 2-7 shows a single track passing loop with a and so prevent point (8) from being reversed. This station. As illustrated there are no trap points at in turn would prevent the down line signals from the ends of the loops to keep trains clear of each being released and allow a down line train to move other. The result is that if two trains approach the into a fouling position. loop at the same time, they would need to brought In Figure 2-7, shunting to the down sidings

3 8 6 C.B. Platform

Up 5 1 2 Down 9 10 7 Platform 13 14 15 5

Goods 4 Shed FIGURE 2-7 Single Track Passing Loop with Station and Siding.

6 - 2 - 8 Part 6 Section 2 LAYOUT OF SIGNALS Issued May 1995

involves access from the up line and the use of a same lever there would be a risk of trapping diamond crossing, a situation that would generally pedestrians on the crossing. The modern four arm be avoided but could arise due to site topography. lifting barrier follows the same principle by lower- If the local road layout required the goods shed to ing the nearside arm against oncoming traffic be located as shown, then, to minimise the number before the offside is lowered protecting the other of shunting movements, a trailing connection to side of the crossing. the up line is needed. However, the more usual A down train could have the down home signal arrangement would be a trailing crossover from restored to ‘on’ behind it and the crossing gates the down line platform which would allow room for opened to road traffic while standing at the plat- shunting while remaining within station limits. form, but an up train must depart before the up The box controlling a track layout as shown on line starting signal can be restored to ‘on’ and road the diagram would need a 15 lever frame with two traffic restored. Where stations have been mod- spare levers. ernised, or in some instances re-opened, a stag- gered platform layout (shown dotted on the up line) has been adopted to minimise the delay to 2.4.3 road traffic.

Level crossing gate locks and wicket gate locks are usually worked by the end levers nearest to the 2.5 Signal Sighting and Siting crossing so that the signalman can watch the road traffic while operating the levers. Wicket gates It is very important for the (Model) Signal were a feature of some of the older gated level Engineer to consider the sighting of signals by crossings where a pedestrian overbridge was not train drivers when he is deciding where to site available. Two wicket locks were provided so that them. For example, on curved track the signal one gate could be locked behind pedestrians on the arms should be set square-on to the driver rather crossing and the second once they has passed clear than at right angles to the track. This is even more of the track. If both gates were controlled by the important with colour light signals because of their narrow-angle light beams. Obstructions such as overbridges have to be considered as these require the use of banner repeaters and/or co-act- Gate Lock 15 Up Up ing signals. Home Starting On multiple tracks great efforts are made to Platform >14 Platform locate the signals on the left hand side of the track Up to which they refer and this can often involve the use of complex brackets and gantries. Where track Down curves to the left, signals may have to be located >13 Platform on the far right side of the track to give longer visi- Down Signal Down bility. For many years the GWR used right hand Starting Box Home drive engines and as a result signals were often placed to right of the track. The position of signals FIGURE 2-8 in relation to the adjacent track was determined Through Station with Level Crossing. by the structure .

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